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Dordt ag department releases 2011 test plot results

Field variety test plot results from the Dordt College agriculture department in Sioux Center are now available.

The field trials were conducted by agriculture majors in Dordt’s Field Crop Production and Management class under the supervision of Dr. Ron Vos, Dordt College professor of agriculture. Their research was in conjunction with the Northwest Iowa On-Farm Research Association with Iowa State Extension. Students who participated in the field sized-comparison study were Devin Bell, Sidney, Mont.; Mia Boonstoppel, Smithfield, New Brunswick; Hannah Clark, Pioneer, Ohio; Kurt Franje, New Sharon, Iowa; Michael Gallagher, Hornick, Iowa; Matthew Kamp, Manhattan, Mont.; Justin Knutson, Centerville, S.D.; Tyler Woodward, Hamburg, Iowa; and Caleb Wubben, Clara City, Minn. They were assisted by Mike Schouten of the Dordt Agriculture Stewardship Center.

Vos noted that this year’s conditions were unique as the season began very wet and ended dry.

Thirteen trials were conducted on Dordt College Ag Stewardship Center fields located north of Sioux Center. The Dordt trials were planted in strips of one or two equipment-widths across the entire field. Because these narrow strips lie close to one another, field variability between treatment strips is minimized. The treatments were replicated at least three times in the field to overcome chance field differences. In addition, the order of the varieties in each block was chosen at random, avoiding a source of unconscious bias.

“We want our data to be accurate and credible, as well as meaningful to the farmers, so we use on-farm sized comparison analysis,” said Vos. Replication, randomization, and field-sized strips ensure the results will be valid and applicable to farmers’ field situations. The students used a measurement called the “least significant difference” (LSD). If the difference between two varieties is greater than the LSD, then the difference is considered significant.

Vos said that Dordt publishes results at an LSD of .05. “This means we are confident that our results are statistically valid 19 out of 20 times.” An LSD of .25, for example, would be valid only three out of four times.